Crosslinked laminate, shape-retaining film, crosslinkable laminate, crosslinkable composition film, tab lead film, battery exterior material, and battery

Abstract

The present invention relates to a crosslinkable composition film which is used after being crosslinked and is used with an adhesive layer laminated on at least one surface, wherein the crosslinkable composition film contains a silane-modified propylene-based polymer and is used as a member of a lithium-ion secondary battery. The crosslinkable composition film preferably contains a crosslinking catalyst. The crosslinkable composition film is preferably disposed between a tab lead and the innermost layer of a battery exterior material.

Description

Crosslinked laminates, shape-retaining films, crosslinkable laminates, crosslinkable composition films, tab lead films, battery casing materials, and batteries

[0001] The present invention relates to a crosslinked laminate, a shape-retaining film, a crosslinkable laminate, and a crosslinkable composition film. The present invention also relates to a battery casing material and a tab lead film having the above-mentioned crosslinked laminate, shape-retaining film, crosslinkable laminate, or crosslinkable composition film, as well as a battery having the above-mentioned battery casing material or tab lead film.

[0002] Lithium-ion rechargeable batteries have been widely used as power sources for various electronic devices such as laptop computers and other office automation equipment, smartphones, game consoles, and electronic organizers, as well as for on-board power supplies in hybrid or electric vehicles and stationary energy storage systems.

[0003] Traditionally, metal cans, formed by press-forming metal into cylindrical or rectangular prism shapes, were used as outer casings for lithium-ion secondary batteries. However, in recent years, in response to the demand for greater flexibility in product shape, laminated outer casings, which are made of a laminate of metal foil and resin in the form of a bag or tray, have come into use as an alternative to the aforementioned metal cans.

[0004] More specifically, the laminated outer container described above consists of a laminate comprising a heat-resistant polymer layer that serves as a protective layer, a metal foil that serves as a base layer, and a heat-sealable polymer layer that is the innermost layer and serves as a sealing layer. When housing the battery body inside, the laminate is formed by drawing to create a recess, the contents of which are the battery body are filled into the recess, and then heat-sealed to seal the contents.

[0005] To increase the adhesive strength between the metal terminals (tab leads) used in the electrodes of lithium-ion secondary batteries and the innermost layer of the outer casing, a configuration is known in which an adhesive layer (e.g., tab lead film) consisting of a single or multilayer structure is further placed between them. As the adhesive layer, there has been much research being conducted on the use of propylene-based polymers, such as modified polypropylene obtained by modifying polypropylene with an unsaturated carboxylic acid or its derivative.

[0006] When a laminated outer container is heat-sealed at a high temperature (e.g., 160°C to 220°C) and high pressure (e.g., 1 MPa), if the adhesive layer cannot sufficiently maintain its thickness and other shape, there is a risk of contact between the tab lead and the metal foil of the laminated outer container, causing a short circuit. For this reason, the adhesive layer is required to have shape retention properties. To improve the shape retention properties of the adhesive layer during heat sealing, it is known that cross-linked polyolefins are used as the material for the adhesive layer or the layer laminated with the adhesive layer (Patent Documents 1 and 2).

[0007] Japanese Patent Publication No. 2014-53316 Japanese Patent Publication No. 2002-279945

[0008] According to the inventors' research, obtaining crosslinked polyolefins as described in Patent Documents 1 and 2 requires irradiation with electron beams, ultraviolet rays, or gamma rays, thus necessitating large-scale equipment. Furthermore, since non-crosslinked layers are prone to degradation by electron beams, ultraviolet rays, or gamma rays, additional steps are required, such as laminating non-crosslinked layers after single-layer crosslinking or adding degradation-suppressing components to non-crosslinked layers. In particular, when the above degradation-suppressing components are added to the adhesive layer, there is a possibility of a decrease in the adhesive performance of the adhesive layer or a change in its thermal properties. The thermal properties of the above adhesive layer should be meticulously designed from a safety standpoint so that the adhesive strength weakens at a predetermined temperature to release pressure in the event of a runaway reaction in the battery. Thus, there is room for improvement in the crosslinked polyolefins described in Patent Documents 1 and 2.

[0009] Therefore, the present invention aims to provide a crosslinked laminate and a shape-retaining film that can be easily manufactured and have excellent shape retention during heat sealing. The present invention also aims to provide a crosslinkable laminate and a crosslinkable composition film. Furthermore, the present invention aims to provide a battery casing material and a tab lead film having the above-mentioned crosslinked laminate, shape-retaining film, crosslinkable laminate, or crosslinkable composition film, as well as a battery having the above-mentioned battery casing material or tab lead film.

[0010] The inventors of the present invention diligently studied to solve the above problems and found that the above problems could be solved by using a shape-retaining layer containing a silane-crosslinked propylene polymer, thus completing the present invention. In other words, the gist of the present invention is as follows.

[0011] Embodiment A1 of the present invention is a crosslinkable composition film that is used by crosslinking and having an adhesive layer laminated on at least one surface, and comprises a silane-modified propylene polymer, and is used as a component of a lithium-ion secondary battery.

[0012] Aspect A2 of the present invention is a crosslinkable composition film according to aspect A1, comprising a crosslinking catalyst.

[0013] Aspect A3 of the present invention is a crosslinkable composition film according to aspect A1 or A2, which is disposed between the tab lead and the innermost layer of the battery casing material.

[0014] Aspect A4 of the present invention is a shape-retaining film obtained by crosslinking the crosslinkable composition film described in Aspect A1 with silane.

[0015] Embodiment A5 of the present invention is a shape-retaining film according to Embodiment A4, comprising a crosslinking catalyst.

[0016] Aspect A6 of the present invention is a shape-retaining film according to aspect A4 or A5, which is placed between the tab lead and the innermost layer of the battery casing material.

[0017] Embodiment A7 of the present invention is a crosslinkable laminate comprising a crosslinkable composition layer which is a crosslinkable composition film as described in Embodiment A1, and an adhesive layer laminated on at least one surface of the crosslinkable composition layer.

[0018] Aspect A8 of the present invention is a crosslinkable laminate according to aspect A7, wherein the crosslinkable composition layer contains a crosslinking catalyst.

[0019] Aspect A9 of the present invention is a crosslinkable laminate according to aspect A7 or A8, wherein the adhesive layer contains an acid-modified polyolefin.

[0020] Embodiment A10 of the present invention is a crosslinkable laminate according to embodiments A7 to A9, comprising one crosslinkable composition layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the crosslinkable composition layer.

[0021] Embodiment A11 of the present invention is a crosslinkable laminate according to any one of embodiments A7 to A10, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the crosslinkable composition layer.

[0022] Embodiment A12 of the present invention is a crosslinkable laminate according to any one of embodiments A7 to A10, which is disposed between the tab lead and the innermost layer of the battery casing material.

[0023] Embodiment A13 of the present invention is a crosslinked laminate obtained by crosslinking the crosslinkable laminate described in Embodiment A7 with silane, and includes a shape-retaining layer obtained by crosslinking the crosslinkable composition layer with silane, and the adhesive layer laminated on at least one surface of the shape-retaining layer.

[0024] Embodiment A14 of the present invention is a crosslinked laminate comprising a shape-retaining layer which is a shape-retaining film as described in Embodiment A4, and an adhesive layer laminated on at least one surface of the shape-retaining layer.

[0025] Embodiment A15 of the present invention is a crosslinked laminate according to Embodiment A13, wherein the gel fraction of the shape-retaining layer measured under the following measurement conditions is 1% or more and 80% or less. Measurement conditions for gel fraction: The crosslinked laminate is subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble matter is measured. The gel fraction is defined as the ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction.

[0026] Embodiment A16 of the present invention is a crosslinked laminate according to Embodiment A13 or A15, wherein the shape-retaining layer contains a crosslinking catalyst.

[0027] Embodiment A17 of the present invention is a crosslinked laminate according to any one of embodiments A13, A15, and A16, wherein the adhesive layer contains an acid-modified polyolefin.

[0028] Aspect A18 of the present invention is the crosslinked laminate according to any one of Aspects A13 and A15 to A17, which includes one layer of the shape-retaining layer and two layers of the adhesive layers, wherein the adhesive layers are laminated on both surfaces of the shape-retaining layer.

[0029] Aspect A19 of the present invention is the crosslinked laminate according to any one of Aspects A13 and A15 to A17, which further includes a tab lead, wherein the tab lead is adhered onto the surface of the adhesive layer on the opposite side to the side in contact with the shape-retaining layer.

[0030] Aspect A20 of the present invention is the crosslinked laminate according to Aspect A18, which further includes a tab lead, wherein the tab lead is adhered onto the surface of the adhesive layer on the opposite side to the side in contact with the shape-retaining layer.

[0031] Aspect A21 of the present invention is the crosslinked laminate according to Aspect A14, wherein the gel fraction of the shape-retaining layer measured under the following measurement conditions is 1% by mass or more and 80% by mass or less. Measurement conditions for gel fraction: The crosslinked laminate is subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble matter is measured. The ratio (%) of the mass of the residue after the Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before the Soxhlet extraction is defined as the gel fraction.

[0032] Aspect A22 of the present invention is the crosslinked laminate according to Aspect A14 or A21, wherein the shape-retaining layer contains a crosslinking catalyst.

[0033] Aspect A23 of the present invention is the crosslinked laminate according to any one of Aspects A14, A21 and A22, wherein the adhesive layer contains acid-modified polyolefin.

[0034] Aspect A24 of the present invention is the crosslinked laminate according to any one of Aspects A14 and A21 to A23, which includes one layer of the shape-retaining layer and two layers of the adhesive layers, wherein the adhesive layers are laminated on both surfaces of the shape-retaining layer.

[0035] Aspect A25 of the present invention is the crosslinked laminate according to any one of Aspect A14 and Aspects A21 to A23, further comprising a tab lead, wherein the tab lead is adhered to a surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

[0036] Aspect A26 of the present invention is the crosslinked laminate according to Aspect A24, further comprising a tab lead, wherein the tab lead is adhered to a surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

[0037] Aspect A27 of the present invention is the crosslinked laminate according to any one of Aspects A13 to A18 and Aspects A21 to A24, which is disposed between a tab lead and the innermost layer of a battery outer packaging material.

[0038] Aspect A28 of the present invention is a member for a lithium ion secondary battery, comprising the crosslinked laminate according to any one of Aspects A13 to A27.

[0039] Aspect A29 of the present invention is a tab lead film, comprising the crosslinked laminate according to any one of Aspects A13 to A18 and Aspects A21 to A24.

[0040] Aspect A30 of the present invention is a lithium ion secondary battery, comprising the tab lead film according to Aspect A29.

[0041] Aspect A31 of the present invention is a battery outer packaging material, comprising the crosslinked laminate according to any one of Aspects A13 to A27.

[0042] Aspect A32 of the present invention is a lithium ion secondary battery, comprising the battery outer packaging material according to Aspect A31.

[0043] Aspect B1 of the present invention is a crosslinked laminate, comprising: a shape-retaining layer containing a silane-crosslinked propylene-based polymer; and an adhesive layer, wherein the adhesive layer is laminated on at least one surface of the shape-retaining layer.

[0044] Embodiment B2 of the present invention is a crosslinked laminate according to Embodiment B1, wherein the gel fraction of the shape-retaining layer measured under the following measurement conditions is 1% or more and 80% or less. Measurement conditions for gel fraction: The crosslinked laminate is subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble matter is measured. The gel fraction is defined as the ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction.

[0045] Embodiment B3 of the present invention is a crosslinked laminate according to Embodiment B1 or B2, wherein the shape-retaining layer contains a crosslinking catalyst.

[0046] Embodiment B4 of the present invention is a crosslinked laminate according to any one of embodiments B1 to B3, wherein the adhesive layer contains an acid-modified polyolefin.

[0047] Embodiment B5 of the present invention is a crosslinked laminate according to any one of embodiments B1 to B4, comprising one shape-retaining layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the shape-retaining layer.

[0048] Embodiment B6 of the present invention is a crosslinked laminate according to any one of embodiments B1 to B4, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

[0049] Embodiment B7 of the present invention is a crosslinked laminate according to Embodiment B5, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

[0050] Embodiment B8 of the present invention is a battery casing material having a crosslinked laminate as described in any one of embodiments B1 to B7.

[0051] Embodiment B9 of the present invention is a battery having the battery casing material described in Embodiment B8.

[0052] Embodiment B10 of the present invention is a shape-retaining film used by laminating an adhesive layer on at least one surface, comprising a silane-crosslinked propylene polymer, and used as a battery casing material.

[0053] Embodiment B11 of the present invention is a shape-retaining film according to Embodiment B10, comprising a crosslinking catalyst.

[0054] Embodiment B12 of the present invention is a crosslinkable laminate comprising a crosslinkable composition layer containing a silane-modified propylene polymer and an adhesive layer, wherein the adhesive layer is laminated on at least one surface of the crosslinkable composition layer.

[0055] Embodiment B13 of the present invention is a crosslinkable laminate according to Embodiment B12, wherein the crosslinkable composition layer contains a crosslinking catalyst.

[0056] Embodiment B14 of the present invention is a crosslinkable laminate according to Embodiment B12 or B13, wherein the adhesive layer contains an acid-modified polyolefin.

[0057] Embodiment B15 of the present invention is a crosslinkable laminate according to any one of embodiments B12 to B14, comprising one crosslinkable composition layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the crosslinkable composition layer.

[0058] Embodiment B16 of the present invention is a crosslinkable laminate according to any one of embodiments B12 to B15, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the crosslinkable composition layer.

[0059] Embodiment B17 of the present invention is a crosslinkable composition film that is used by crosslinking and having an adhesive layer laminated on at least one surface, and contains a silane-modified propylene polymer, and is used as a battery casing material.

[0060] Embodiment B18 of the present invention is a crosslinkable composition film according to Embodiment B17, comprising a crosslinking catalyst.

[0061] According to the present invention, it is possible to provide a crosslinked laminate and a shape-retaining film that can be easily manufactured and have excellent shape retention during heat sealing. Furthermore, it is possible to provide a crosslinkable laminate and a crosslinkable composition film for obtaining the above-mentioned crosslinked laminate and shape-retaining film. The above-mentioned crosslinked laminate, shape-retaining film, crosslinkable laminate and crosslinkable composition film are useful as battery components such as battery casing materials or tab lead films.

[0062] The embodiments of the present invention will be described in detail below, but the following embodiments are examples (representative examples) of embodiments of the present invention, and the present invention is not limited thereto. The present invention can be modified and implemented as such without departing from its spirit. In this specification, when "~" is used to express numerical values ​​or physical properties before and after it, it is intended to include the values ​​before and after it. Also, in this specification, "mass%" and "weight%", and "parts by mass" and "parts by weight" are synonymous.

[0063] 《Crosslinkable Composition Film》 The present invention relates to a crosslinkable composition film. The crosslinkable composition film according to this embodiment is a crosslinkable composition film that is used by crosslinking and by laminating an adhesive layer on at least one surface, and contains a silane-modified propylene polymer, and is used as a battery component such as a battery casing material or tab lead film, particularly as a component of a lithium-ion secondary battery.

[0064] (Silane-modified propylene polymer) The silane-modified propylene polymer contained in the crosslinkable composition film is not particularly limited as long as it is obtained by reacting a propylene polymer with an unsaturated silane compound. The propylene polymer reacted with the unsaturated silane compound may be a propylene homopolymer or a copolymer of propylene and another monomer (hereinafter also referred to as "propylene copolymer"). The form of the propylene copolymer may be a block copolymer, a random copolymer, or a mixture thereof. Furthermore, one type of propylene polymer may be used, or two or more types may be used in combination.

[0065] As other monomers for the above-mentioned propylene copolymer, α-olefins are preferred, that is, the propylene copolymer is preferably a propylene-α-olefin copolymer. As the propylene-α-olefin copolymer, for example, any of the following can be used: propylene-ethylene copolymer, propylene-1-butene copolymer, propylene-ethylene-1-butene copolymer, etc.

[0066] When the propylene polymer is a propylene copolymer, the propylene unit content of the propylene copolymer is preferably 30% by mass or more and less than 100% by mass. From the viewpoint of heat resistance, electrolyte resistance, and adhesion to polypropylene used in the innermost layer of the outer container, the above content is preferably 30% by mass or more, more preferably 40% by mass or more, and even more preferably 50% by mass or more. The above propylene unit content can be measured, for example, by NMR.

[0067] The melt flow rate (MFR) of the propylene polymer is not particularly limited, but is preferably 0.1 to 120 g / 10 min. Here, the MFR of the above propylene polymer is usually 0.1 g / 10 min or more, but from the viewpoint of moldability of the shape-retaining layer, it is preferably 0.3 g / 10 min or more, and more preferably 0.5 g / 10 min or more. Also, the MFR of the above propylene polymer is usually 120 g / 10 min or less, but from the same viewpoint as above, it is preferably 100 g / 10 min or less, more preferably 80 g / 10 min or less, even more preferably 60 g / 10 min or less, and particularly preferably 40 g / 10 min or less. In this specification, the MFR of the propylene polymer is the value measured at a temperature of 230°C, a load of 21.2 N, and an orifice diameter of 2 mm, referring to JIS K 7210:1999.

[0068] The density of propylene polymers is 0.850–0.930 g / cm³. ３ Preferably, 0.855 to 0.920 g / cm³ ３ This is more preferable. In this specification, the density of the propylene polymer is the value measured with reference to JIS K 7112:1999.

[0069] Propylene polymers may be manufactured or commercially available. Examples of commercially available polymers include the Novatec® series, Newcon® series, Wintec® series, Wellnex® series, and Waymax® series from Nippon Polypropylene Co., Ltd., and the Zelas® series from Mitsubishi Chemical Corporation.

[0070] The unsaturated silane compound to be reacted with the propylene-based polymer is also not particularly limited, but a compound represented by the following formula (1) is preferred. One type of unsaturated silane compound may be used alone, or two or more types may be used in combination. R １ Si(R ２ ) ３ ...(1) (In the above formula (1), R １ is an olefinically unsaturated hydrocarbon group, and R ２ each independently represents a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, and at least one of R ２ is an alkoxy group having 1 to 10 carbon atoms.)

[0071] In the above formula (1), R １ is an olefinically unsaturated hydrocarbon group, preferably an olefinically unsaturated hydrocarbon group having 2 to 10 carbon atoms, and more preferably an olefinically unsaturated hydrocarbon group having 2 to 6 carbon atoms. More specific examples of R １ include alkenyl groups such as a vinyl group, a propenyl group, a butenyl group, and a cyclohexenyl group.

[0072] In the above formula (1), R ２ each independently represents a hydrocarbon group having 1 to 10 carbon atoms or an alkoxy group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 6 carbon atoms or an alkoxy group having 1 to 6 carbon atoms, and more preferably a hydrocarbon group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. Further, at least one of R ２ is an alkoxy group having 1 to 10 carbon atoms, preferably an alkoxy group having 1 to 6 carbon atoms, and more preferably an alkoxy group having 1 to 4 carbon atoms.

[0073] R ２ When R is a hydrocarbon group having 1 to 10 carbon atoms, the hydrocarbon group may be any of an alkyl group, an aliphatic group, an alicyclic group, or an aromatic group, and is preferably an alkyl group. Specific examples of R ２ include alkyl groups typified by a methyl group, an ethyl group, an isopropyl group, a t-butyl group, an n-butyl group, an i-butyl group, a cyclohexyl group and the like, and aryl groups typified by a phenyl group and the like.

[0074] R ２ When is an alkoxy group having 1 to 10 carbon atoms, the alkoxy group may be linear, branched, or cyclic, but linear or branched is preferred. ２ Specifically, these include methoxy groups, ethoxy groups, isopropoxy groups, and β-methoxyethoxy groups.

[0075] When an unsaturated silane compound is represented by the above formula (1), there are three R ２ At least one of them is an alkoxy group having 1 to 10 carbon atoms, but there are two or more R ２ Preferably, the group is an alkoxy group, and all R ２ It is more preferable that the group is an alkoxy group.

[0076] Among the unsaturated silane compounds represented by formula (1) above, vinyltrialkoxysilanes, such as vinyltrimethoxysilane, vinyltriethoxysilane, and propenyltrimethoxysilane, are more preferred. This is because the vinyl group enables modification to a propylene-based polymer, and the alkoxy group facilitates the following crosslinking reaction.

[0077] The above crosslinking reaction first involves introducing alkoxy groups, which have been grafted onto a propylene polymer using an unsaturated silane compound, reacting with water in the presence of a crosslinking catalyst to undergo hydrolysis and generate silanol groups. Then, the resulting silanol groups undergo dehydration condensation, causing the modified propylene polymers to bond together and resulting in a crosslinking reaction.

[0078] The amount of modification of the unsaturated silane compound in the silane-modified propylene polymer, i.e., the amount of unsaturated silane compound introduced into the silane-modified propylene polymer by graft modification, is preferably 0.1 to 5.0% by mass. Here, from the viewpoint of heat resistance, the above modification amount is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.3% by mass or more. Also, from the viewpoint of moldability, the above modification amount is preferably 5.0% by mass or less, more preferably 4.0% by mass or less, and even more preferably 3.0% by mass or less. The amount of modification of the unsaturated silane compound is the mass ratio of the unsaturated silane compound introduced by graft modification to the propylene polymer before modification.

[0079] The silane-modified propylene polymer described above may be graft-modified using compounds other than unsaturated silane compounds in combination, as long as the effects of the present invention are not impaired. Examples of compounds other than unsaturated silane compounds include unsaturated carboxylic acids such as acrylic acid, methacrylic acid, ethacrylic acid, maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, and isocrotonic acid, as well as their acid anhydrides.

[0080] The above-mentioned silane-modified propylene polymer can be produced by graft-modifying a propylene polymer with the above-mentioned unsaturated silane compound. There are no particular restrictions on the graft modification method, and conventionally known methods can be used. For example, solution modification, melt modification, solid-phase modification by irradiation with electron beams or ionizing radiation, and modification in a supercritical fluid are suitably used. Among these, melt modification is preferred due to its superior equipment and cost competitiveness, and melt-kneading modification using an extruder, which offers excellent continuous productivity, is even more preferred.

[0081] Examples of equipment used for melt-mixing and modification include single-screw extruders, twin-screw extruders, Banbury mixers, and roll mixers. Among these, single-screw extruders and twin-screw extruders are preferred due to their superior continuous production capabilities.

[0082] Generally, graft modification of propylene polymers with unsaturated silane compounds is carried out by a graft reaction in which the carbon-hydrogen bonds of the propylene polymer are cleaved to generate carbon radicals, to which unsaturated functional groups are added.

[0083] In addition to the electron beams and ionizing radiation mentioned above, methods such as high temperatures and the use of radical generators such as organic and inorganic peroxides can also be employed as sources of carbon radicals. From the viewpoint of cost and ease of operation, the use of organic peroxides is preferable. One type of radical generator may be used alone, or two or more types may be used in combination.

[0084] There are no limitations on the radical generators used in the production of silane-modified propylene polymers, but examples of organic peroxides include the hydroperoxide group, dialkylperoxide group, diacylperoxide group, peroxyester group, and ketoneperoxide group. Azo compounds and the like can also be used as radical generators.

[0085] Among the radical generators listed above, the hydroperoxide group includes cumene hydroperoxide, t-butyl hydroperoxide, etc. The dialkylperoxide group includes dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di-t-butylperoxyhexane, 2,5-dimethyl-2,5-di-t-butylperoxyhexyne-3, etc. The diacylperoxide group includes lauryl peroxide, benzoyl peroxide, etc. The peroxyester group includes t-butylperoxy-2-ethylhexanoate, t-peroxyacetate, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, etc. The ketone peroxide group includes cyclohexanone peroxide, etc. Examples of azo compounds include azobisisobutyronitrile and methyl azoisobutyrate.

[0086] A commonly used melt extrusion modification procedure involves mixing a propylene polymer, an unsaturated silane compound, and a radical generator to obtain a propylene polymer composition. This composition is then fed into a kneader or extruder, where it is extruded while being heated, melt-kneaded, and the molten resin coming out of the end die is cooled in a water bath or the like to obtain a silane-modified propylene polymer.

[0087] The blending ratio of the propylene polymer to the unsaturated silane compound in the above-mentioned propylene polymer composition is not particularly limited, but for example, it is preferable that the blending ratio of the unsaturated silane compound is 0.5 to 10 parts by mass per 100 parts by mass of the propylene polymer. Here, from the viewpoint of obtaining a predetermined amount of modification necessary to achieve the desired effect, the above blending ratio is preferably 0.5 parts by mass or more, and more preferably 1 part by mass or more. Furthermore, from the viewpoint of suppressing the residue of a large amount of unreacted unsaturated silane compound that adversely affects performance, the above blending ratio is preferably 10 parts by mass or less, and more preferably 5 parts by mass or less.

[0088] The blending ratio of the unsaturated silane compound to the radical generator in the above propylene polymer composition is not particularly limited, but for example, it is preferable that the blending ratio of the radical generator is 0.1 to 100 parts by mass per 100 parts by mass of the unsaturated silane compound. Here, from the viewpoint of generating a sufficient amount of radicals and easily obtaining the required predetermined amount of modification, the blending ratio is preferably 0.1 parts by mass or more, and more preferably 10 parts by mass or more. Furthermore, from the viewpoint of suppressing the degradation of the propylene polymer, the blending ratio is preferably 100 parts by mass or less, and more preferably 70 parts by mass or less.

[0089] In addition to the components described above, the propylene polymer composition may contain other additives or other resins other than propylene polymers, depending on the purpose, as long as they do not significantly impair the effects of the present invention.

[0090] Other additives include antioxidants, lubricants, colorants, heat stabilizers, light stabilizers, UV absorbers, neutralizing agents, antifogging agents, antiblocking agents, slip agents, flame retardants, dispersants, antistatic agents, conductivity imparters, metal deactivators, molecular weight modifiers, antibacterial agents, fluorescent whitening agents, and crystal nucleating agents. Depending on the purpose, these may be used individually or in combination of two or more.

[0091] Examples of antioxidants include phenolic antioxidants, phosphite antioxidants, and thioether antioxidants. When using an antioxidant, it is preferable to use it in an amount of 0.1 to 30 parts by mass per 100 parts by mass of the propylene polymer.

[0092] Examples of lubricants include polyethylene wax, oleic acid amide, erucic acid amide, silicone oil, and fluororesins. When using a lubricant, it is preferable to use it in an amount of 0.1 to 10 parts by mass per 100 parts by mass of the propylene polymer.

[0093] Other resins include styrene-based thermoplastic elastomers, polyester resins, polyamide resins, styrene resins, acrylic resins, polycarbonate resins, polyvinyl chloride resins, and various elastomers (excluding those corresponding to the propylene-based polymers mentioned above). The other resins listed above may be used individually or in combination of two or more. It is preferable to use a total of 50 parts by mass or less of the other resins per 100 parts by mass of the propylene-based polymer.

[0094] For example, in single-screw and twin-screw extruders, it is preferable to extrude the propylene polymer composition at a temperature of approximately 150 to 300°C under the melt extrusion modification conditions.

[0095] The silane-modified propylene polymer described above may be manufactured or commercially available. A suitable commercially available option is, for example, one from Mitsubishi Chemical's Linkron® series.

[0096] The MFR of the above silane-modified propylene polymer is not particularly limited, but is preferably 0.1 to 50 g / 10 min. Here, from the viewpoint of moldability of the shape-retaining film or shape-retaining layer, the MFR of the above silane-modified propylene polymer is preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more, even more preferably 0.8 g / 10 min or more, and particularly preferably 1 g / 10 min or more. Also, from the same viewpoint as above, the MFR of the above silane-modified propylene polymer is preferably 50 g / 10 min or less, more preferably 40 g / 10 min or less, even more preferably 30 g / 10 min or less, and particularly preferably 20 g / 10 min or less. In this specification, the MFR of the silane-modified propylene polymer is the value measured at a temperature of 230°C, a load of 21.2 N, and an orifice diameter of 2 mm, based on JIS K 7210:1999.

[0097] The content of the silane-modified propylene polymer in the crosslinkable composition film is preferably 50 to 100% by mass. From the viewpoint of shape retention, the above content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0098] (Crosslinking catalyst) The crosslinkable composition film according to this embodiment preferably contains a crosslinking catalyst that catalyzes the dehydration condensation between silanol groups. Examples of crosslinking catalysts include one or more compounds selected from the group consisting of metal organic salts, titanates, borates, organic amines, ammonium salts, phosphonium salts, inorganic acids and organic acids, and inorganic acid esters.

[0099] Examples of the above metal organic salts include, but are not limited to, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dioctoate, stannous acetate, stannous octanoate, cobalt naphthenate, lead octoate, lead naphthenate, zinc octoate, zinc caprylate, iron 2-ethylhexanoate, iron octoate, and iron stearate. Examples of the above titanates include, but are not limited to, tetrabutyl titanate, tetranonyl titanate, and bis(acetylacetonitrile) diisopropyl titanate. Examples of the above organic amines include, but are not limited to, ethylamine, dibutylamine, hexylamine, triethanolamine, dimethyl soyamine, tetramethylguanidine, and pyridine. Examples of the above ammonium salts include, but are not limited to, ammonium carbonate and tetramethylammonium hydroxide. Examples of the above phosphonium salts include, but are not limited to, tetramethylphosphonium hydroxide. Examples of the inorganic and organic acids mentioned above include, but are not limited to, sulfonic acid compounds such as sulfuric acid, hydrochloric acid, acetic acid, stearic acid, maleic acid, toluenesulfonic acid, and alkylnaphthylsulfonic acid. Examples of the inorganic acid esters mentioned above are not particularly limited, but include phosphate esters.

[0100] Among these, metal organic acid salts, sulfonic acid compounds, and phosphate esters are preferred, and more preferably are tin metal carboxylates, such as dioctyl tin dilaurate, alkyl naphthyl sulfonic acid, and ethylhexyl phosphate ester. Furthermore, from the viewpoint of environmental impact, crosslinking performance, and suppression of yellowing of the shape-retaining layer, zinc compounds represented by the following formula (2) are preferred. Zn(OCOR) ３ ) (OCOR ４ ) ... (2) (In equation (2), R ３ and R ４ Each of these is independently a saturated hydrocarbon group. ３ and R ４Preferably, each of these is a branched saturated hydrocarbon group having 9 to 11 carbon atoms. The crosslinking catalyst may be used alone or in combination of two or more types as appropriate.

[0101] When the crosslinkable composition film contains the above-mentioned crosslinking catalyst, the amount of the crosslinking catalyst in the crosslinkable composition film is not particularly limited, but from the viewpoint of suppressing premature crosslinking during molding of the crosslinkable composition film before crosslinking and promoting the crosslinking reaction during the production of the silane-crosslinked propylene polymer, and improving the heat resistance of the resulting crosslinked laminate or shape-retaining film, it is preferably 0.01 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of the silane-modified propylene polymer.

[0102] Furthermore, it is preferable to use the crosslinking catalyst as a crosslinking catalyst-containing masterbatch, which is a mixture of a resin and the crosslinking catalyst. Examples of resins that can be used in this crosslinking catalyst-containing masterbatch include homopolypropylene, which is a polymer of propylene; copolymers of propylene and ethylene or α-olefins such as butene, hexene, octene (excluding propylene); and ethylene copolymers. Among these, homopolypropylene and propylene-ethylene copolymers are preferred from the viewpoint of heat resistance, flexibility, etc. Here, it is preferable that the propylene-ethylene copolymer is obtained by copolymerizing 60 to 98% by mass of propylene and 2 to 40% by mass of ethylene. Furthermore, in the masterbatch of the crosslinking catalyst, only one of these polypropylenes may be used alone, or two or more may be used in appropriate combinations.

[0103] When using a crosslinking catalyst as a crosslinking catalyst-containing masterbatch, which is a mixture of a resin and the crosslinking catalyst, there are no particular restrictions on the content of the crosslinking catalyst in the masterbatch, but it is preferable to set it to, for example, about 0.1 to 5.0% by mass. A commercially available product can be used as the crosslinking catalyst-containing masterbatch; for example, Mitsubishi Chemical's "PZ010" can be used.

[0104] The thickness of the crosslinkable composition film according to this embodiment is preferably 5 to 300 μm. From the viewpoint of thickness stability during molding and shape retention effect, the above thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of size when used in battery components such as battery casing material or tab lead film, the above thickness is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and particularly preferably 100 μm or less.

[0105] The crosslinkable composition film according to this embodiment is used by crosslinking and by laminating an adhesive layer on at least one surface. Furthermore, the crosslinkable composition film according to this embodiment is used in battery components such as battery casings or tab lead films, particularly in lithium-ion secondary batteries. The crosslinking method is the same as that described later in the section on "Shape-retaining films." The adhesive layer is the same as that described later in the section on the adhesive layer of the "Crosslinkable laminate." The crosslinkable composition film becomes the shape-retaining film according to this embodiment when crosslinked. Furthermore, the crosslinkable composition film is used as a crosslinkable composition layer, and an adhesive layer is laminated on at least one surface to form a crosslinkable laminate according to this embodiment. Moreover, the crosslinkable composition film becomes a crosslinkable laminate according to this embodiment when crosslinked and an adhesive layer is laminated on at least one surface. Furthermore, the embodiments for use in battery components such as battery casings or tab lead films are the same as those described later in the section on "Applications of Crosslinkable Laminates." The crosslinkable composition film according to this embodiment is preferably used as a tab lead film, placed between the electrode (tab lead) and the innermost layer of the battery casing.

[0106] 《Method for Manufacturing Crosslinkable Composition Films》 One method for manufacturing crosslinkable composition films is to extrude a crosslinkable composition containing a silane-modified propylene polymer. A crosslinking catalyst may be added to the above crosslinkable composition in advance.

[0107] 《Shape-retaining film》 The present invention also relates to a shape-retaining film. The shape-retaining film according to this embodiment is obtained by crosslinking the above-mentioned crosslinkable composition film with silane. In other words, the shape-retaining film according to this embodiment is a shape-retaining film used by laminating an adhesive layer on at least one surface, and contains a silane-crosslinked propylene polymer, and is used as a battery component such as a battery casing material or tab lead film, particularly as a component of a lithium-ion secondary battery.

[0108] (Silane-crosslinked propylene polymer) The silane-crosslinked propylene polymer contained in the shape-retaining film is obtained by a crosslinking reaction between the above-mentioned silane-modified propylene polymers. Specifically, for example, a crosslinkable composition containing the above-mentioned silane-modified propylene polymer can be crosslinked by exposing it together with the above-mentioned crosslinking catalyst to an aqueous atmosphere and allowing the crosslinking reaction between silanol groups to proceed.

[0109] Various conditions can be used for exposure to a watery atmosphere. For example, methods include leaving the object in air containing moisture, blowing air containing water vapor, immersing it in a water bath, and spraying warm water in a mist.

[0110] In the crosslinking reaction between silanol groups, hydrolyzable alkoxy groups in the silane-modified propylene polymer react with water in the presence of a crosslinking catalyst to hydrolyze and generate silanol groups. Then, the resulting silanol groups undergo dehydration condensation, which drives the crosslinking reaction, causing the silane-modified propylene polymers to bond together and form a silane-crosslinked propylene polymer.

[0111] The rate of the crosslinking reaction depends on the conditions under which the material is exposed to a water atmosphere. For example, it is preferable to expose the material to a water atmosphere in a temperature range of 20 to 130°C and for a period of 10 minutes to 2 weeks. More preferable conditions are a temperature range of 60 to 110°C and a period of 1 hour to 160 hours. When using air containing moisture as the method of exposure to a water atmosphere, the relative humidity of the air is selected from the range of 1 to 100% RH. Particularly preferred conditions include moist heat treatment at 85 to 95°C and 85 to 100% RH for 16 to 32 hours.

[0112] The gel fraction (degree of crosslinking) of the shape-retaining film containing a silane-crosslinked propylene polymer is preferably 1% to 80%. The gel fraction is the mass ratio of the insoluble portion after xylene boiling point extraction, and is specifically measured under the following conditions. For the shape-retaining film according to this embodiment, Soxhlet extraction is performed in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble portion is measured. The ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining film before Soxhlet extraction is defined as the gel fraction. From the viewpoint of measurement accuracy, the thickness of the shape-retaining film used for the above measurement of the gel fraction is preferably 1 mm or less.

[0113] From the viewpoint of shape retention of the shape-retaining film, the above gel fraction is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 10% or more. Furthermore, from the viewpoint of adhesion to the polypropylene polymer used in the innermost layer of the outer container, the above gel fraction is preferably 80% or less, more preferably 70% or less, and even more preferably 60% or less.

[0114] The gel fraction described above can be adjusted by changing the grafting rate (amount of modification) of the unsaturated silane compound in the silane-modified propylene polymer, the type and amount of the crosslinking catalyst, and the conditions (temperature, time) during crosslinking.

[0115] The content of the silane-crosslinked propylene polymer in the shape-retaining film is preferably 50 to 100% by mass. From the viewpoint of shape retention, the above content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0116] The shape-retaining film according to this embodiment preferably contains a crosslinking catalyst that catalyzes the dehydration condensation between silanol groups. Examples of crosslinking catalysts are the same as those described in the "Crosslinkable Composition Film" section above.

[0117] When the shape-retaining film contains the above-mentioned crosslinking catalyst, the amount of the crosslinking catalyst in the shape-retaining film is not particularly limited, but from the viewpoint of suppressing premature crosslinking during the molding of the shape-retaining film before crosslinking, promoting the crosslinking reaction during the production of the silane-crosslinked propylene polymer, and improving the heat resistance of the resulting shape-retaining film, it is preferably 0.01 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of the silane-crosslinked propylene polymer.

[0118] The thickness of the shape-retaining film according to this embodiment is preferably 5 to 300 μm. From the viewpoint of thickness stability during molding and shape retention effect, the above thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of size when used in battery components such as battery casing material or tab lead film, the above thickness is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and particularly preferably 100 μm or less.

[0119] The shape-retaining film according to this embodiment is used by laminating an adhesive layer on at least one surface and is used in battery components such as battery casings or tab lead films, particularly in components of lithium-ion secondary batteries. The adhesive layer is the same as that described in the section on the adhesive layer of the "crosslinkable laminate" described later. The shape-retaining film becomes a crosslinked laminate according to this embodiment when an adhesive layer is laminated on at least one surface. Furthermore, the embodiments used in battery components such as battery casings or tab lead films are the same as those described in the section on "Applications of Crosslinked Laminates" described later. The shape-retaining film according to this embodiment is preferably used as a tab lead film, that is, placed between the electrode (tab lead) and the innermost layer of the battery casing.

[0120] 《Method for Manufacturing Shape-Retaining Films》 One method for manufacturing shape-retaining films is to blend a crosslinking catalyst into a crosslinkable composition containing a silane-modified propylene polymer, extrude it, and then crosslink it.

[0121] 《Crosslinkable Laminate》 The present invention also relates to a crosslinkable laminate. The crosslinkable laminate according to this embodiment includes a crosslinkable composition layer which is the crosslinkable composition film described above, and an adhesive layer laminated on at least one surface of the crosslinkable composition layer. In other words, the crosslinkable laminate according to this embodiment includes a crosslinkable composition layer which contains a silane-modified propylene polymer, and an adhesive layer, wherein the adhesive layer is laminated on at least one surface of the crosslinkable composition layer.

[0122] The crosslinkable composition layer included in the crosslinkable laminate according to this embodiment contains a silane-modified propylene polymer. When the above crosslinkable composition layer is crosslinked, a crosslinkable laminate with excellent shape retention during heat sealing is obtained. The silane-modified propylene polymer is the same as that described in the "Crosslinkable Composition Film" above.

[0123] The content of the silane-modified propylene polymer in the crosslinkable composition layer is preferably 50 to 100% by mass. From the viewpoint of shape retention, the above content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0124] The crosslinkable composition layer included in the crosslinkable laminate according to this embodiment preferably contains a crosslinking catalyst that catalyzes the dehydration condensation between silanol groups. Examples of crosslinking catalysts are the same as those described in the "Crosslinkable Composition Film" section above.

[0125] When the crosslinkable composition layer contains the above-mentioned crosslinking catalyst, the amount of the crosslinking catalyst in the crosslinkable composition layer is not particularly limited, but from the viewpoint of suppressing premature crosslinking during molding of the crosslinkable composition layer before crosslinking and promoting the crosslinking reaction during the production of the silane-crosslinked propylene polymer, and improving the heat resistance of the resulting crosslinked laminate, it is preferably 0.01 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of the silane-modified propylene polymer.

[0126] In addition to the components described above, the crosslinkable composition layer may contain other additives and other resins other than silane-modified propylene polymers, depending on the purpose, as long as they do not significantly impair the effects of the present invention. Examples of other additives and other resins are the same as those described above as components that may be included in the propylene polymer composition in the "crosslinkable composition film".

[0127] <Adhesive Layer> The adhesive layer included in the crosslinkable laminate according to this embodiment may have adhesive properties, but it is preferable that it consists of an adhesive composition containing, for example, an acid-modified polyolefin.

[0128] (Acid-modified polyolefins) There are no particular restrictions on the acid-modified polyolefins, and conventionally known ones can be used. Acid-modified polyolefins are obtained by graft copolymerizing polyolefins such as polyethylene, polypropylene, ethylene-α-olefin copolymers, ethylene-α-olefin-non-conjugated diene copolymers (EPDM, etc.), and ethylene-aromatic monovinyl compound-conjugated diene copolymer rubbers using, for example, unsaturated carboxylic acids such as maleic acid, unsaturated carboxylic acid derivatives (including anhydrides such as maleic anhydride), or combinations thereof. This graft copolymerization is carried out, for example, by reacting the above polyolefin with an unsaturated carboxylic acid, its derivative, or combination thereof in a suitable solvent using a radical generator such as benzoyl peroxide. Unsaturated carboxylic acids, their derivatives, or combinations thereof can also be introduced into the polymer chain by random or block copolymerization with polyolefin monomers.

[0129] Examples of unsaturated carboxylic acids used for modification include compounds having polymerizable double bonds into which carboxyl groups and, if necessary, functional groups such as hydroxyl groups or amino groups have been introduced, such as maleic acid, fumaric acid, itaconic acid, acrylic acid, and methacrylic acid. Derivatives of unsaturated carboxylic acids include their acid anhydrides, esters, amides, imides, and metal salts. Specific examples include maleic anhydride, itaconic anhydride, methyl acrylate, ethyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, monoethyl maleate, diethyl maleate, monomethyl fumarate, dimethyl fumarate, acrylamide, methacrylamide, monoamide maleate, diamide maleate, monoamide fumarate, maleimide, N-butylmaleimide, and sodium methacrylate. Maleic anhydride is preferred.

[0130] Examples of graft reaction conditions include dialkyl peroxides such as di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyisopropyl carbonate, and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane. One method involves reacting organic peroxides, such as peroxyesters including 2,5-dimethyl-2,5-di(benzoylperoxy)hexyne-3, diacylperoxides including benzoylperoxide, diisopropylbenzene hydroperoxide, and hydroperoxides including 2,5-dimethyl-2,5-di(hydroperoxy)hexane, in an amount of about 0.001 to 10 parts by mass per 100 parts by mass of the polyolefin, at a temperature of about 80 to 300°C, either in a molten or solution state.

[0131] The amount of acid modification of the acid-modified polyolefin is not particularly limited, but is preferably 0.05 to 10% by mass, more preferably 0.07 to 5% by mass, in terms of maleic anhydride. The above amount of acid modification can be measured by known methods, for example, by the method described in Japanese Patent Publication No. 2011-074398.

[0132] From the standpoint of the magnitude of the effects in the present invention, preferred acid-modified polyolefins include maleic anhydride-modified propylene-ethylene copolymer and maleic anhydride-modified polypropylene.

[0133] The adhesive composition constituting the adhesive layer preferably contains 0.1 to 50% by mass of the above-mentioned acid-modified polyolefin. From the viewpoint of adhesion, the above content is preferably 0.5% by mass or more, more preferably 1% by mass or more, and even more preferably 1.5% by mass or more.

[0134] The adhesive composition may contain additives, resins, etc. (hereinafter sometimes referred to as "other components") in addition to the acid-modified polyolefin described above, to the extent that they do not significantly impede the effects of the present invention. The other components may be used individually or in any combination and ratio of two or more types.

[0135] The additives that can be used in the adhesive composition are not limited, but specifically include heat stabilizers, weather stabilizers (antioxidants, light stabilizers, UV absorbers, etc.), flame retardants, foaming agents, antiblocking agents, slip agents, antistatic agents, fillers (inorganic fillers, organic fillers, or combinations thereof, etc.), processing aids, plasticizers, crystal nucleating agents, impact modifiers, compatibilizers, catalyst residue neutralizers, carbon black, and colorants (pigments, dyes, etc.). When these additives are used, their content is not limited, but it is preferably 0.01% by mass or more, more preferably 0.2% by mass or more, and more preferably 5% by mass or less, and more preferably 2% by mass or less, relative to the adhesive composition.

[0136] The adhesive composition may also contain a tackifier as another component. Here, the tackifier is an amorphous resin that is solid at room temperature, such as petroleum resin, rosin resin, terpene resin, or hydrogenated versions thereof. However, if the adhesive composition contains a large amount of tackifier, it may cause smoke generation during molding or reduce heat resistance. For this reason, even when a tackifier is used, it is preferable to use 30% by mass or less in the adhesive composition, more preferably 20% by mass or less, and particularly preferably 10% by mass or less. Even without using a tackifier, the above adhesive composition exhibits excellent low-temperature processability and good adhesion to tab leads, and can maintain good adhesion to tab leads even in high-temperature and high-humidity environments.

[0137] Examples of petroleum resins used as tackifiers include aliphatic petroleum resins, aromatic petroleum resins, copolymers thereof, and hydrogenated versions thereof. Examples of petroleum resin skeletons include C5 resins, C9 resins, C5 / C9 copolymer resins, cyclopentadiene resins, polymers of vinyl-substituted aromatic compounds, copolymers of olefins / vinyl-substituted aromatic compounds, copolymers of cyclopentadiene compounds / vinyl-substituted aromatic compounds, and hydrogenated versions thereof. Rosin resins used as tackifiers are natural resins mainly composed of abietic acid, and examples include natural rosin, polymerized rosin derived from natural rosin, stabilized rosin obtained by disproportionating or hydrogenating natural rosin or polymerized rosin, unsaturated acid-modified rosin obtained by adding unsaturated carboxylic acids to natural rosin or polymerized rosin, natural rosin esters, modified rosin esters, and polymerized rosin esters. Examples of terpene resins used as tackifiers include polyterpene resins, aromatic terpene resins such as terpene phenol resins, aromatic-modified terpene resins, and hydrogenated versions thereof.

[0138] The resins used as other components are not limited, but examples include polyolefins, polyphenylene ethers, polycarbonates, polyamides such as nylon 66 and nylon 11, polyesters such as polyethylene terephthalate and polybutylene terephthalate, styrene polymers such as polystyrene, and acrylic / methacrylic polymers such as polymethyl methacrylate. Polyolefin resins such as propylene copolymers and ethylene copolymers are particularly preferred.

[0139] The MFR of the adhesive composition constituting the adhesive layer is not particularly limited, but is preferably 0.1 to 30 g / 10 min. Here, from the viewpoint of moldability of the adhesive layer, the MFR of the adhesive composition is preferably 0.1 g / 10 min or more, more preferably 0.5 g / 10 min or more, and even more preferably 1 g / 10 min or more. Also, from the same viewpoint as above, the MFR of the adhesive composition is preferably 30 g / 10 min or less, more preferably 25 g / 10 min or less, even more preferably 20 g / 10 min or less, even more preferably 15 g / 10 min or less, and particularly preferably 10 g / 10 min or less. In this specification, the MFR of the adhesive composition is the value measured according to JIS K 7210:1999 at a temperature of 230°C, a load of 21.2 N, and an orifice diameter of 2 mm.

[0140] In the crosslinkable laminate according to this embodiment, the thickness of the crosslinkable composition layer is preferably 5 to 300 μm. From the viewpoint of thickness stability during molding and shape retention effect, the above thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of size when used in battery components such as battery casing material or tab lead film, the above thickness is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and particularly preferably 100 μm or less.

[0141] In the crosslinkable laminate according to this embodiment, the thickness of the adhesive layer is preferably 5 to 200 μm. From the viewpoint of thickness stability and adhesion during molding, the above thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of shape retention effect, the above thickness is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less.

[0142] The crosslinkable laminate according to this embodiment has a structure in which an adhesive layer is laminated on at least one surface of a crosslinkable composition layer. The crosslinkable laminate may consist of only one crosslinkable composition layer and one adhesive layer. On the other hand, the crosslinkable laminate may include one crosslinkable composition layer and two adhesive layers, with adhesive layers laminated on both surfaces of the crosslinkable composition layer, that is, it may have a three-layer structure of adhesive layer-crosslinkable composition layer-adhesive layer.

[0143] <Tab Leads> The crosslinkable laminate according to this embodiment may further include tab leads. When the crosslinkable laminate includes tab leads, the tab leads are adhered to the surface of the adhesive layer opposite to the side that is in contact with the crosslinkable composition layer.

[0144] The above-mentioned tab leads may consist of only one or two. If the crosslinkable laminate according to this embodiment consists of only one crosslinkable composition layer and one adhesive layer, one or two tab leads are adhered to the surface of the adhesive layer. If the crosslinkable laminate according to this embodiment has a three-layer structure of adhesive layer-crosslinkable composition layer-adhesive layer and there is one tab lead, the tab lead is adhered to the surface of either one of the adhesive layers. If the crosslinkable laminate according to this embodiment has a three-layer structure of adhesive layer-crosslinkable composition layer-adhesive layer and there are two tab leads, the two tab leads may be adhered to the surface of only one of the adhesive layers, or one tab lead may be adhered to the surface of each of the two adhesive layers.

[0145] Tab leads contain metal. Examples of metals that make up tab leads include aluminum, nickel, copper, stainless steel, titanium, steel and their alloys, as well as metal-plated metal materials. Among these, aluminum, nickel, or nickel-plated copper are preferred, and nickel-plated copper is more preferred because it is resistant to corrosion by strong acids and has high electrical conductivity. When a crosslinkable laminate contains two tab leads, the metals that make up both may be the same or different.

[0146] The tab lead may have a single-layer structure or a multi-layer structure in which two or more layers containing different metals are laminated together. The method for manufacturing the multi-layer tab lead is not particularly limited and includes methods such as co-extrusion film method, dry lamination method, wet lamination method, hot melt lamination method, extrusion lamination method, and thermal lamination method.

[0147] The thickness of the tab lead is not particularly limited, but is preferably 9 to 200 μm, more preferably 15 to 100 μm, and even more preferably 20 to 80 μm, considering barrier properties, pinhole resistance, and processability.

[0148] The crosslinkable laminate according to this embodiment is preferably used after crosslinking, and is preferably used as a battery component such as a battery casing or tab lead film, particularly as a component of a lithium-ion secondary battery. The crosslinking method is the same as that described in the section on "Shape-Retaining Films" above. The crosslinking treatment crosslinks the crosslinkable composition layer, resulting in the crosslinkable laminate according to this embodiment. Unlike conventional methods using crosslinked polyolefins that require crosslinking by irradiation with electron beams, ultraviolet rays, or gamma rays, the non-crosslinked layers are less susceptible to degradation. Therefore, using the crosslinkable laminate according to this embodiment eliminates the need for procedures such as laminating non-crosslinked layers after single-layer crosslinking, or adding degradation-suppressing components to non-crosslinked layers, allowing for the simple manufacture of a crosslinkable laminate. Furthermore, the embodiments of using the crosslinkable laminate as a battery component such as a battery casing or tab lead film are the same as those described in the section on "Applications of Crosslinkable Laminates" below. The crosslinkable laminate according to this embodiment is preferably used as a tab lead film, positioned between the electrode (tab lead) and the innermost layer of the battery casing.

[0149] 《Method for Manufacturing Crosslinkable Laminates》 Various known methods can be used to manufacture the crosslinkable laminate according to this embodiment. For example, there is inflation molding by co-extrusion, in which individual molten resins melted in an extruder are supplied to a multilayer die and laminated in the die; film molding or sheet molding by T-die molding; container molding by blow molding; and co-injection molding, in which molten individual resins are injected into the same mold with a time lag. In addition, extrusion lamination by co-extrusion of the adherend or with other resins, or a method in which the adherend is subjected to corona discharge treatment or flame treatment before lamination and the adhesive surface of the adherend and adhesive layer is treated with ozone immediately before lamination can also be used. Furthermore, a lamination method by heat lamination, heat sealing, etc., of the crosslinkable composition film of the present invention obtained by co-extrusion of the adherend or with other resins and an adhesive film can also be used.

[0150] 《Crosslinked Laminate》 The crosslinked laminate according to this embodiment includes a shape-retaining layer containing a silane-crosslinked propylene polymer and an adhesive layer, wherein the adhesive layer is laminated on at least one surface of the shape-retaining layer. Specifically, the crosslinked laminate according to this embodiment includes an embodiment in which the above-mentioned crosslinkable laminate is crosslinked with silane, and the crosslinkable composition layer is crosslinked with silane, and the adhesive layer is laminated on at least one surface of the shape-retaining layer; and an embodiment in which the crosslinked laminate includes a shape-retaining layer which is the above-mentioned shape-retaining film and an adhesive layer is laminated on at least one surface of the shape-retaining layer.

[0151] In the crosslinked laminate according to this embodiment, the thickness of the shape-retaining layer is preferably 5 to 300 μm. From the viewpoint of thickness stability during molding and shape retention effect, the above thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of size when used in battery components such as battery casing material or tab lead film, the above thickness is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 150 μm or less, and particularly preferably 100 μm or less.

[0152] In the crosslinked laminate according to this embodiment, the thickness of the adhesive layer is preferably 5 to 200 μm. From the viewpoint of thickness stability and adhesion during molding, the thickness is preferably 5 μm or more, more preferably 10 μm or more, even more preferably 15 μm or more, and particularly preferably 20 μm or more. Furthermore, from the viewpoint of shape retention effect, the thickness is preferably 200 μm or less, more preferably 150 μm or less, even more preferably 100 μm or less, and particularly preferably 50 μm or less.

[0153] The crosslinked laminate according to this embodiment has a configuration in which an adhesive layer is laminated on at least one surface of a shape-retaining layer. The crosslinked laminate may consist of only one shape-retaining layer and one adhesive layer. On the other hand, the crosslinked laminate may include one shape-retaining layer and two adhesive layers, with adhesive layers laminated on both surfaces of the shape-retaining layer, that is, it may have a three-layer structure of adhesive layer-shape-retaining layer-adhesive layer.

[0154] <Shape-retaining layer> The shape-retaining layer included in the crosslinked laminate according to this embodiment contains a silane-crosslinked propylene polymer. By including such a shape-retaining layer, the crosslinked laminate according to this embodiment can be easily manufactured and has excellent shape retention during heat sealing. Furthermore, compared to conventional crosslinked polyolefins crosslinked using electron beams, ultraviolet rays, or gamma rays, the silane-crosslinked propylene polymer has a lower water permeability. Therefore, when the crosslinked laminate according to this embodiment is used as a battery component, the barrier function is enhanced, and the ingress of moisture from the air into the electrolyte can be suppressed.

[0155] The above-mentioned silane-crosslinked propylene polymer is obtained by a crosslinking reaction between silane-modified propylene polymers. The characteristics of the silane-modified propylene polymer are the same as those described in the "Crosslinkable Composition Film" section above. The method for obtaining the silane-crosslinked propylene polymer is the same as that described in the "Shape-Retaining Film" section above.

[0156] The gel fraction (degree of crosslinking) of the shape-retaining layer containing the silane-crosslinked propylene polymer is preferably 1% to 80%. The gel fraction is the mass ratio of the insoluble portion after xylene boiling point extraction, and is specifically measured under the following conditions. For the crosslinked laminate according to this embodiment, Soxhlet extraction is performed in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble portion is measured. The ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction is defined as the gel fraction. Here, it is assumed that the adhesive layer contained in the crosslinked laminate dissolves 100% in boiling xylene. The mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction is estimated from the mass of the crosslinked laminate and the thicknesses of the shape-retaining layer and the adhesive layer, assuming that the thickness and weight of the layer are proportional. The thickness of the shape-retaining layer used for the measurement of the gel fraction is preferably 1 mm or less from the viewpoint of measurement accuracy.

[0157] From the viewpoint of maintaining the shape of the crosslinked laminate, the gel fraction is preferably 1% or more, more preferably 3% or more, even more preferably 5% or more, and particularly preferably 10% or more. Furthermore, from the viewpoint of adhesion to the polypropylene polymer used in the innermost layer of the outer container, the gel fraction is preferably 80% or less, more preferably 70% or less, and even more preferably 60% or less.

[0158] The gel fraction described above can be adjusted by changing the grafting rate (amount of modification) of the unsaturated silane compound in the silane-modified propylene polymer, the type and amount of the crosslinking catalyst, and the conditions (temperature, time) during crosslinking.

[0159] The content of the silane-crosslinked propylene polymer in the shape-retaining layer is preferably 50 to 100% by mass. From the viewpoint of shape retention, the above content is preferably 50% by mass or more, more preferably 60% by mass or more, even more preferably 70% by mass or more, and particularly preferably 80% by mass or more.

[0160] The shape-retaining layer of the crosslinked laminate according to this embodiment preferably contains a crosslinking catalyst that catalyzes the dehydration condensation between silanol groups. Examples of crosslinking catalysts include those described in the "Crosslinkable Composition Film" section above.

[0161] When the shape-retaining layer contains the crosslinking catalyst, the amount of the crosslinking catalyst in the shape-retaining layer is not particularly limited, but from the viewpoint of suppressing premature crosslinking during the molding of the laminate before crosslinking and promoting the crosslinking reaction during the production of the silane-crosslinked propylene polymer, and improving the heat resistance of the resulting crosslinked laminate, it is preferably 0.01 to 0.5 parts by mass, and more preferably 0.03 to 0.3 parts by mass, per 100 parts by mass of the silane-crosslinked propylene polymer.

[0162] The crosslinked laminate according to this embodiment includes an adhesive layer. The adhesive layer is the same as that described in the section on the adhesive layer of the "crosslinkable laminate" above.

[0163] The crosslinked laminate according to this embodiment can be suitably used as a battery casing material or a battery component such as a tab lead film having the same. Furthermore, this battery casing material or battery component such as a tab lead film can be suitably used as a battery having the same.

[0164] The crosslinked laminate according to this embodiment may further include tab leads. The bonding position and material of the tab leads in the crosslinked laminate may be the same as those described for the tab leads in the "Crosslinkable Laminate" above.

[0165] 《Method for Manufacturing a Crosslinked Laminate》 The method for manufacturing the crosslinked laminate according to this embodiment is not particularly limited. One method for manufacturing a crosslinked laminate is to produce the shape-retaining film described above and apply the adhesive composition described above to one or both surfaces thereof to form an adhesive layer. Another method is to produce the shape-retaining film described above and bond an adhesive composition film made of the adhesive composition described above to one or both surfaces thereof to form an adhesive layer. Yet another method is to produce the crosslinkable laminate described above and perform a crosslinking treatment thereon.

[0166] <Applications of the Crosslinked Laminate> The crosslinked laminate according to this embodiment can be used as a battery casing material or a battery component such as a tab lead film, particularly as a component of a lithium-ion secondary battery. Furthermore, the battery casing material or the battery component such as a tab lead film can be used in a battery.

[0167] A battery consists of a positive electrode, a negative electrode, a separator separating them, and an electrolyte filling the gap, all sealed by a battery casing material. It also includes metal terminals for electrically connecting the electrodes to an external circuit. The battery casing material is a laminate composed of a heat-resistant polymer layer serving as a protective layer, a metal foil serving as a base layer, and a heat-sealable polymer layer that is the innermost layer and serves as a sealing layer. The crosslinked laminate according to this embodiment is preferably placed between the electrodes (tab leads) and the innermost layer of the battery casing material, i.e., used as a tab lead film. In this case, the tab leads may also be considered as part of the crosslinked laminate according to this embodiment. Because the crosslinked laminate according to this embodiment can be easily manufactured, the manufacturing process for battery components such as the battery casing material or tab lead film, and for the battery itself, can also be simplified. Furthermore, because the crosslinked laminate according to this embodiment has excellent shape retention during heat sealing, it can suppress short circuits caused by contact between the tab leads and the metal foil of the battery casing material.

[0168] The battery may be either a primary battery or a secondary battery, but a secondary battery is preferred. The type of secondary battery is not particularly limited and examples include lithium-ion batteries, lithium-ion polymer batteries, lead-acid batteries, nickel-metal hydride batteries, nickel-cadmium batteries, nickel-iron batteries, nickel-zinc batteries, silver oxide-zinc batteries, metal-air batteries, polyvalent cation batteries, capacitors, and the like. Among these secondary batteries, lithium-ion batteries and lithium-ion polymer batteries are preferred applications for the crosslinked laminate according to this embodiment.

[0169] The present invention will be described in more detail below with reference to examples, but the present invention is not limited in any way by these examples. The various manufacturing conditions and evaluation result values ​​in the following examples are meant to represent preferred upper or lower limits in the embodiments of the present invention, and the preferred range may be defined by a combination of the aforementioned upper or lower limits and the values ​​of the following examples or the values ​​of the examples themselves.

[0170] The raw materials used in the example are listed below.

[0171] ・A-1: Propylene homopolymer, MFR: 0.5 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm) ・A-2: Propylene homopolymer, MFR: 0.4 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm) ・A-3: Propylene-ethylene random copolymer, MFR: 0.8 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm), propylene unit content 97% by mass, ethylene unit content 3% by mass ・A-4: Propylene homopolymer, MFR: 0.4 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm) ・A-5: Propylene homopolymer, MFR: 2.8 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm) • A-6: Propylene-ethylene copolymer, MFR: 1.2 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm), propylene unit content 89% by mass, ethylene unit content 11% by mass • A-7: Propylene-ethylene copolymer, MFR: 1.4 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm), propylene unit content 84% by mass, ethylene unit content 16% by mass • A-8: Ethylene-(1-octene) copolymer, MFR: 0.5 g / 10 min (190°C, load 21.2 N, orifice diameter 2 mm), ethylene unit content 58% by mass, 1-octene unit content 42% by mass・A-9: Propylene-ethylene copolymer, MFR: 0.8 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm), propylene unit content 79% by mass, ethylene unit content 21% by mass ・A-10: Propylene-ethylene copolymer, MFR: 8.0 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm), propylene unit content 91% by mass, ethylene unit content 9% by mass ・A-11: Low-density polyethylene, MFR: 4.0 g / 10 min (190°C, load 21.2 N, orifice diameter 2 mm) ・A-12: Modified propylene-ethylene copolymer (Method for manufacturing A-12) 100 parts by mass of propylene-ethylene random copolymer (MFR (230°C, load 21.2N): 2g / 10min, ethylene ratio: 11% by mass) was dry-blended and mixed with 1.5 parts by mass of maleic anhydride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and 1.5 parts by mass of organic peroxide (manufactured by NOF Corporation, perbutyl O).Next, the obtained mixture was melt-kneaded and pelletized using a twin-screw extruder (D=30 mmφ, L / D=32, manufactured by Japan Steel Works Ltd., TEX30) at a temperature of 200°C, a screw rotation speed of 300 rpm, and an extrusion rate of 10 kg / h. This yielded modified propylene-ethylene random copolymer A-12, grafted with maleic anhydride, with a modification amount of 1.1 mass%. The MFR of A-12 (180°C, 21.2 N load, 1 mm orifice diameter) was 0.5 g / 10 min.

[0172] • B-1: Organic peroxide t-butylperoxy-2-ethylhexanoate, Perbutyl O (registered trademark) (manufactured by NOF Corporation) • B-2: Unsaturated silane compound vinyltrimethoxysilane KBM-1003 (manufactured by Shin-Etsu Chemical Co., Ltd.) • B-3: Lubricant polyethylene wax, ACumist (registered trademark) B-6 (Honeywell Corporation) • B-4: Crosslinking catalyst masterbatch PZ010 (manufactured by Mitsubishi Chemical Corporation), 1% tin catalyst-containing polypropylene, MFR: 16 g / 10 min (230°C, load 21.2 N, orifice diameter 2 mm) • B-5: Organic peroxide Niper (registered trademark) BMT-K40 (manufactured by NOF Corporation)

[0173] <Manufacturing Examples> <Manufacturing Examples 1-1 to 1-8: Preparation of Silane-Modified Propylene Polymers> The components listed in the <Raw Materials> above were dry-blended and mixed in the amounts shown in Table 1. However, B-4 (crosslinking catalyst masterbatch) was added when used in the test examples described later. In the table, blank spaces indicate that the corresponding component was not included. The obtained mixture was melt-kneaded using a twin-screw extruder (bore diameter 30 mmφ) at a set temperature of 220°C, a screw rotation speed of 400 rpm, and an extrusion rate of 20 kg / h, and a pellet-shaped silane-modified propylene polymer (crosslinkable composition) was obtained by strand cutting. The MFR (230°C, load 21.2 N) of the obtained silane-modified propylene polymer was measured by the method described later, and the results are shown in Table 1.

[0174] <Production Example 2-1: Preparation of Adhesive Composition> 80 parts by mass of A-10, 10 parts by mass of A-11, and 10 parts by mass of A-12, as described in the above <Raw Materials>, were dry-blended and mixed. The resulting mixture was melt-kneaded using a twin-screw extruder (bore diameter 30 mmφ) at a set temperature of 220°C, a screw rotation speed of 400 rpm, and an extrusion rate of 20 kg / h, and a pellet-shaped adhesive composition (Production Example 2-1) was obtained by strand cutting. The MFR (230°C, load 21.2 N) of the obtained adhesive composition was measured and found to be 9 g / 10 min.

[0175] <Test Example 1> <Preparation of Crosslinkable Composition Film> Using the silane-modified propylene polymer (crosslinkable composition) obtained in each of the production examples 1-1 to 1-7, single-layer crosslinkable composition films were prepared as follows. Five parts by mass of catalyst masterbatch B-4 were dry-blended into the compositions obtained in the production examples. An extrusion sheet molding machine (manufactured by Thermoplastics Industries Co., Ltd.) with a T-die in an extruder with a diameter of 20 mmφ was used, and the temperature of the composition to be melted was set to 220°C, and the cooling roll surface temperature to 30-80°C. Using the above compositions, the extrusion amount and take-up speed were adjusted so that the film width was 100 mm and the thickness was 100 μm to obtain the crosslinkable composition films of Examples 1 to 7.

[0176] <Crosslinking treatment of crosslinkable composition film> The crosslinkable composition film obtained above was cut to a size of 100 mm x 50 mm and subjected to moist heat treatment at 85°C, 85% RH for 16 hours to crosslink with silane, thereby obtaining the shape-retaining films of Examples 1 to 7.

[0177] The thickness retention rate before and after heat sealing, and the improvement rate of thickness retention rate before and after crosslinking, of the crosslinkable composition films (before crosslinking) and shape-retaining films (after crosslinking) of the obtained Examples 1 to 7 were measured using the method described later, and the results are shown in Table 2.

[0178] <Measurement and Evaluation> The evaluation methods for various physical properties of raw material polymers, silane-modified propylene polymers (crosslinkable compositions), and silane-crosslinked propylene polymers are as follows.

[0179] (Melt Flow Rate (MFR)) The MFR of each raw material polymer and silane-modified propylene polymer (crosslinkable composition) was measured in accordance with JIS K7210 (1999) under the conditions of a measurement temperature of 190°C or 230°C, a load of 21.2 N, and an orifice diameter of 2 mm.

[0180] (Gel fraction) To 100 parts by mass of the silane-modified propylene polymer (crosslinkable composition) obtained in each of the production examples, 5 parts by mass of the crosslinking catalyst masterbatch (B-4) were added and blended, and the mixture was molded in an injection molding machine under conditions of 220°C to create a crosslinkable composition sheet with a thickness of 1 mm. The obtained crosslinkable composition sheet was subjected to moist heat treatment at 85°C, 85% RH for 16 hours to crosslink with silane and create a shape-retaining sheet. The obtained shape-retaining sheet was subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble matter was measured. The ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining sheet before Soxhlet extraction was defined as the gel fraction. The gel fraction measured in this way can be considered to reflect the gel fraction of the shape-retaining films of Examples 1 to 7.

[0181] (Thickness retention rate before and after heat sealing of crosslinkable composition film and shape-retaining film single layer) For each of the crosslinkable composition film (before crosslinking) and shape-retaining film (after crosslinking) prepared in Test Example 1, the thickness was measured at an arbitrary position in the center in the TD direction to obtain the thickness before heat sealing. This sample was sandwiched between PET films from above and below, and pressure was applied at 220°C, 0.8 MPa, and a pressing time of 60 seconds, so that the long side of the 5 cm x 10 cm cut film was parallel to the heat sealing bar and the position where the thickness was measured overlapped with the heat sealing bar. For the sample obtained by this operation, the thickness was measured at the same position as before heat sealing to obtain the thickness after heat sealing. The thickness retention rate was calculated from "thickness after heat sealing / thickness before heat sealing × 100 (%)". The thickness retention rate is an indicator of the shape retention of the sample. A high thickness retention rate can be evaluated as good, and a thickness retention rate of 70% or more is considered to be sufficient for practical use. The reason for setting a thickness retention rate of 70% or more as sufficient for practical use is as follows. To maintain insulation between the tab lead and the metal foil of the laminate outer container and to prevent short circuits, it is generally considered sufficient for the shape-retaining film to have a thickness of 3 μm or more after heat sealing (see, for example, paragraph

[0012] of Japanese Patent No. 4923327). In this embodiment, the thickness of the shape-retaining film is preferably 5 μm or more, and if the thickness retention rate is 70% or more, the thickness of the shape-retaining film after heat sealing will be 3.5 μm or more, which can sufficiently maintain insulation. Furthermore, the thickness retention rate improvement rate was also calculated from "thickness retention rate after crosslinking / thickness retention rate before crosslinking × 100 (%)". The thickness retention rate improvement rate serves as an indicator of the effect of crosslinking on the shape retention of the sample.

[0182]

[0183] As shown in Table 2, the shape-retaining films of Examples 1 to 7, which are shape-retaining films according to this embodiment, exhibited a high level of thickness retention, an indicator of shape retention, of 70% or more. Furthermore, the thickness retention improved before and after heat sealing compared to before crosslinking of the silane-modified propylene polymer, with the improvement rate exceeding 100%.

[0184] <Test Example 2> <Preparation of Crosslinkable Composition Film> Using the silane-modified propylene polymer (crosslinkable composition) obtained in Production Examples 1-8, a single-layer crosslinkable composition film was prepared in the same manner as in Test Example 1.

[0185] <Preparation of Adhesive Composition Film> Using the adhesive composition obtained in Production Example 2-1, an adhesive composition film was prepared using the same method as the preparation method for the crosslinkable composition film described above. However, the temperature of the melting composition was set to 200°C, and the extrusion amount and take-up speed were adjusted so that the thickness was 20 to 30 μm to obtain the adhesive composition film.

[0186] <Preparation of Crosslinkable Laminate> The crosslinkable composition film and adhesive composition film obtained above were each cut to a size of 100 mm x 50 mm. The adhesive composition film and crosslinkable composition film were sandwiched from above and below with PET film, and pressure was applied at 220°C, 0.8 MPa, and a pressing time of 3 seconds so that the long side of the cut film was parallel to the heat seal bar, thereby obtaining the crosslinkable laminate of Example 8, which consists of an adhesive layer and a crosslinkable composition layer.

[0187] <Preparation of Crosslinked Laminates> The crosslinkable composition film and adhesive composition film obtained above were each cut to a size of 100 mm x 50 mm. The cut crosslinkable composition film was subjected to moist heat treatment at 95°C, 100% RH for 16 hours to crosslink with silane and obtain a shape-retaining film. One adhesive composition film and one shape-retaining film were superimposed, sandwiched from above and below with PET film, and pressed at 220°C, 0.8 MPa, and for a pressing time of 3 seconds so that the long side of the cut film was parallel to the heat seal bar, thereby obtaining the crosslinked laminate of Example 8 consisting of one adhesive layer and one shape-retaining layer. The thickness retention rate before and after heat sealing and the thickness retention rate improvement rate before and after crosslinking of the obtained crosslinkable laminate of Example 8 (before crosslinking) and crosslinked laminate (after crosslinking) were measured using the method described later, and the results are shown in Table 3.

[0188] <Measurement and Evaluation> (Gel Fraction) The gel fraction was measured using the silane-modified propylene polymer (crosslinkable composition) obtained in Production Examples 1-8, in the same manner as in Test Example 1. The gel fraction measured in this manner can be considered to reflect the gel fraction of the shape-retaining layer in the crosslinked laminate of Example 8.

[0189] (Thickness retention rate of crosslinkable laminates and crosslinked laminates before and after heat sealing) For the crosslinkable laminate (before crosslinking) and crosslinked laminate (after crosslinking) prepared in Test Example 2, the thickness was measured at an arbitrary position in the center in the TD direction to obtain the total thickness of the laminate before heat sealing. In addition, the thickness of each layer constituting the laminate was measured by cross-sectional observation. This sample was sandwiched between PET films from above and below, and pressure was applied at 220°C, 0.8 MPa, and a pressing time of 60 seconds, with the long side of a 5 cm x 10 cm cut film parallel to the heat sealing bar and the position where the thickness was measured overlapping the heat sealing bar. For the sample obtained by this operation, the thickness was measured at the same position as before heat sealing to obtain the total thickness of the laminate after heat sealing. Similarly, the thickness of each layer constituting the laminate was measured by cross-sectional observation. The thickness retention rate was calculated from "thickness after heat sealing / thickness before heat sealing × 100 (%)". The thickness retention rate is an indicator of the shape retention of the sample. Samples with a high thickness retention rate are considered good, with a rate of 70% or higher being considered practical. The reason for setting a practical thickness retention rate of 70% or higher is the same as described above. Furthermore, the thickness retention rate improvement rate was calculated from "thickness retention rate after crosslinking / thickness retention rate before crosslinking × 100 (%)". The thickness retention rate improvement rate serves as an indicator of the effect of crosslinking on the shape retention of the sample. In Table 3, in the column for thickness retention rate improvement rate, "Crosslinkable composition layer (before crosslinking) → Shape retention layer (after crosslinking)" refers to the thickness retention rate improvement rate calculated based on a comparison between the thickness retention rate of the crosslinkable composition layer (before crosslinking) and the thickness retention rate of the shape retention layer (after crosslinking), which are layers constituting the laminate, and "Crosslinkable laminate (before crosslinking) → Crosslinked laminate (after crosslinking)" refers to the thickness retention rate improvement rate calculated based on a comparison between the thickness retention rate of the crosslinkable laminate (before crosslinking) and the thickness retention rate of the crosslinked laminate (after crosslinking), which are the entire laminate.

[0190]

[0191] As shown in Table 3, the crosslinked laminate of Example 8, which is a crosslinked laminate according to this embodiment, and the shape-retaining layer constituting it, exhibited a high level of thickness retention, an indicator of shape retention, of 70% or more. Furthermore, the thickness retention rate before and after heat sealing was improved compared to before crosslinking of the silane-modified propylene polymer, with the improvement rate exceeding 100%.

[0192] Based on the above, it has been confirmed that the single-layer shape-retaining film or the multi-layer crosslinked laminate according to this embodiment exhibits excellent shape retention during heat sealing.

[0193] Although the present invention has been described in detail with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications are possible without departing from the spirit and scope of the invention. This application is based on Japanese Patent Application No. 2025-050247, filed on 25 March 2025, which is incorporated herein by reference in its entirety.

Claims

1. A crosslinkable composition film used by crosslinking and having an adhesive layer laminated on at least one surface, comprising a silane-modified propylene polymer, and used as a component of a lithium-ion secondary battery.

2. A crosslinkable composition film according to claim 1, comprising a crosslinking catalyst.

3. A crosslinkable composition film according to claim 1 or 2, which is disposed between the tab lead and the innermost layer of the battery casing material.

4. A shape-retaining film obtained by crosslinking a crosslinkable composition film according to claim 1 with silane.

5. The shape-retaining film according to claim 4, comprising a crosslinking catalyst.

6. The shape-retaining film according to claim 4 or 5, which is disposed between the tab lead and the innermost layer of the battery casing material.

7. A crosslinkable laminate comprising a crosslinkable composition layer which is a crosslinkable composition film according to claim 1, and an adhesive layer laminated on at least one surface of the crosslinkable composition layer.

8. The crosslinkable laminate according to claim 7, wherein the crosslinkable composition layer contains a crosslinking catalyst.

9. The crosslinkable laminate according to claim 7, wherein the adhesive layer contains an acid-modified polyolefin.

10. The crosslinkable laminate according to claim 7, comprising one crosslinkable composition layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the crosslinkable composition layer.

11. The crosslinkable laminate according to any one of claims 7 to 10, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the crosslinkable composition layer.

12. A crosslinkable laminate according to any one of claims 7 to 10, disposed between the tab lead and the innermost layer of the battery casing material.

13. A crosslinked laminate comprising a crosslinkable laminate according to claim 7, wherein the crosslinkable laminate comprises a shape-retaining layer formed by crosslinking the crosslinkable composition layer with silane, and the adhesive layer laminated on at least one surface of the shape-retaining layer.

14. A crosslinked laminate comprising a shape-retaining layer which is a shape-retaining film as described in claim 4, and an adhesive layer laminated on at least one surface of the shape-retaining layer.

15. The crosslinked laminate according to claim 13, wherein the gel fraction of the shape-retaining layer measured under the following measurement conditions is 1% or more and 80% or less. Measurement conditions for gel fraction: The cross-linked laminate is subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying out the insoluble matter is measured. The gel fraction is defined as the ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction.

16. The crosslinked laminate according to claim 13, wherein the shape-retaining layer contains a crosslinking catalyst.

17. The crosslinked laminate according to claim 13, wherein the adhesive layer contains an acid-modified polyolefin.

18. The crosslinked laminate according to claim 13, comprising one shape-retaining layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the shape-retaining layer.

19. The crosslinked laminate according to claim 13, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

20. The crosslinked laminate according to claim 18, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

21. The crosslinked laminate according to claim 14, wherein the gel fraction of the shape-retaining layer measured under the following measurement conditions is 1% or more and 80% or less. Measurement conditions for gel fraction: The crosslinked laminate is subjected to Soxhlet extraction in boiling xylene at 144°C for 16 hours, and the mass of the residue after drying the insoluble matter is measured. The ratio (%) of the mass of the residue after Soxhlet extraction to the mass of the shape-retaining layer in the crosslinked laminate before Soxhlet extraction is defined as the gel fraction.

22. The crosslinked laminate according to claim 14, wherein the shape-retaining layer contains a crosslinking catalyst.

23. The crosslinked laminate according to claim 14, wherein the adhesive layer contains an acid-modified polyolefin.

24. The crosslinked laminate according to claim 14, comprising one shape-retaining layer and two adhesive layers, wherein the adhesive layers are laminated on both surfaces of the shape-retaining layer.

25. The crosslinked laminate according to claim 14, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

26. The crosslinked laminate according to claim 24, further comprising a tab lead, wherein the tab lead is adhered to the surface of the adhesive layer opposite to the side in contact with the shape-retaining layer.

27. A crosslinked laminate according to any one of claims 13 to 18 and 21 to 24, which is disposed between the tab lead and the innermost layer of the battery casing material.

28. A component for a lithium-ion secondary battery having a crosslinked laminate according to any one of claims 13 to 26.

29. A tab lead film having a crosslinked laminate according to any one of claims 13 to 18 and 21 to 24.

30. A lithium-ion secondary battery having the tab lead film described in claim 29.

31. A battery casing material having a crosslinked laminate according to any one of claims 13 to 26.

32. A lithium-ion secondary battery having the battery casing material described in claim 31.

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